The present invention relates in general to switching apparatus and more particularly to switching circuits for controlling magnetic latching relays. More specifically, the present invention relates to a circuit particularly useful for controlling magnetic latching relays in programmable attenuators.
Previous switching methods for controlling magnetic latching relays in programmable attenuators have generally utilized a polarity-reversing device such as a double-pole double-throw relay or toggle switch connected in a polarity-reversing mode. Although, in general, these methods were satisfactory, they resulted in an energizing current being applied to the relay coil continuously even through the energizing current was not needed once a relay had been latched. In cases where toggle switches were used, the relay settings (and consequently the attenuation) could not be changed quickly since each relay was controlled by a separate toggle switch.